wolfdad warned me

[Gary O]

Just Friday Doc was telling me that the drawback to the JetCat turbine was the belt. It got me today. I was doing a demo flight for a club flyin today and the belt broke. Somehow it got into the canopy and shoved it into the blades. that was all she wrote. It folded a blade and spiraled to the turf. There is not much left to keep. It pretty much destroyed the heli. It caught fire and had to be shot it with the extinguisher.
The turbine is locked. It is also caved in on one side. Not sure there is any need to even think about trying to rebuild it at this point. The only positive I took away from the whole thing is that it was not something I did wrong.

[WayneBrown]

Oh man, that sucks!
Sorry to hear of your loss........

[fitenfyr]

Ouch.....:(

That sure has me thinking twice about the Jetcat when I get there....
The Wren is starting to look better everyday...

[Greg Alderman]

Gary...man that sucks...very sorry to hear about this. Heard of belts breaking before but this is the first one I have heard of completely destroying the heli...

I had a little excitement myself yesterday at the Rochester, NY event...after flying my last flight Saturday afternoon I auto'ed the Bergen Turbine down and just as I touched down there was a "POP" and the whole canopy area became engulfed in flames! My Spotter "Beast" was quick on the CO2 bottle as I shut the turbine down...the fire was almost out by the time he hit it with CO2 and the shot of CO2 instantly put out any remaining flames…

Either a gas line popped out of a "festo" fitting or a gas line ruptured and let the onboard gas bottle to blow the PowerMax gas directly into the exhaust stream which flashed the gas!!!

I was very lucky as upon post inspection the only damage I have is a couple of inches of melted gas line and my "revolution" antenna wire is a little melted...I was lucky!

I am now thinking about not using the onboard gas supply...at the Liberty Bell Jet Rally I attended a few weeks ago I see a lot of the fixed wing guy have gone away from the onboard system and just connect the bottle up during start up and then remove it when the engine is running on Kero...

If I had a JetCat I would for certain enable the "in-flight" burn of the on board gas now...but the Wren FADEC doesn't have that feature...

[Gary O]

After looking at it again this morning, it didn't look any better in the light of a new day. The main shaft is bent almost a full 90*. It pulled the mounts through both tanks, and the turbine has a nasty cave in on one side. I'm really starting to think this one is a total loss.

[wolfdad]

Gary,
Man! I am indeed sorry to hear about your mishap. We may differ in brand preferences, however we ALL HATE to hear about anyone's mishap.

Additionally, for all of you who take the time to read this post, I along with Greg am going to NO onboard propane. I had three good starts testing the system out with an external Powermax source with plenty of time to disconnect and clear the aircraft.

Greg's experience this weekend was enough "hand-writing on the wall" to convince me. And, if you have a Jetcat, may I recommend you set up the option to empty that cannister so you have no onboard gas stored while inflight. A minor mishap could be turned into a disaster if the remaining onboard Powermax has the chance to flash, then ignite the JP. Just my two cents worth.

Gary, again, I feel really badly for you, shipmate and hope you will be flying again soon.
Doc

[wolfdad]

Gary,
Sincerely, I am NOT trying to beat a dead horse or prolong your misery, however I would be very interested, having owned a Jetcat, to see any pictures you may care to share with us. Again, I know the "sinking feeling" you are going through and I am sure I speak for the rest of the folks in the forum, that, if there is anything we can do to help, all you gotta' do is ask.
Doc

[Gary O]

I've never posted pics before so it might take me a little while to figure out how. I'll get them posted as soon as I can.

[Peter Rob]

Hi Doc there is another photo in my gallery
I have the kit to rebuild but too busy on other projects
Peter R
http://www.helifreak.com/album_mod/upload/7d45d9b5bc1a3550e65b5c8a72a9be90.jpg

[richie1967_uk]

Man that is a mess. My commiserations to you. You have helped me with a decision i have been pondering over for a while, and that is (like wolfdad and Mr Bergen) to do away with the onboard gas system. I am building a cuatro and there is not much room for it all anyway. On a cold day i have been using a large bottle connected to the system anyway (as it was too cold to get good enough gas pressure with the small bottle). It actually is not a problem, just disconnect when the turbine is at idle.

[Peter Rob]

Richie, I have just fitted the kero-start to my JetCat SPH5, I have had a couple of starts just to basically prime and bleed the system the Acrobatic is now ready for flying, just waiting for the weather
Peter R

[wolfdad]

Wow! And, OUCH! That was a nasty one!
Doc

[Coolice]

Hey Guys,

This is not nice to see, I'm sorry for all you guys that have damaged models in accidents.

It does go on to highlight what could happen and from that both myself and other visitors to this forum will be better informed because of it.

After reading through the thread now even I am considering removing the gas bottle from my Predator now, then using the one way valve connect up the propane bottle just for starting.
May look into this as now I am pushing the model through more technical manouvers, it would be all to easy for me to get it wrong accidentally :badair:
.

[wolfdad]

Peter gave me some amplifying remarks regarding his crash and it seems the majority of the fire resulted from ruptured fuel cells. That having been said, I still believe that flying with any onboard start gas poses a very real and potent explosive hazard and am now building all of my turbine aircraft whether pod and boom or scale for external start gas starting. After Greg's inflight experience last year, I am convinced that is the way to go, Safety has to be our number one priority and I am convinced that carrying a container of compressed, highly flammable gas on board is asking for it....and, should a line rupture or come loose and the gas ignite, it could be the difference in saving or losing a very valuable aircraft. I am really happy to see some other folks considering the same options. Perhaps a threat describing how each of us does this might be in order....very easy to do, BTW.
Doc

[Dr.Tim]

Last weekend in Las Vegas I was helping out a young Fellow (ANYONE UNDER 45!! ) with his Jetcat powered EC ... well after a few failed starts I asked him to check things out as there was only a little Smoke comeing from the pipes. He informed me he had the Kero Start and sometimes it did this, We found his NMH Batt was bad ... We dug up a Nicad!! And tried it again!! The Hot start was incredable!!!! The Flames shot out over the tail and continued to GRO as the turbine spooled up!! He wanted to shut it down but, I advised against it!! Well, after 30 seconds the flames were shooting past the tail and into the fenstron!! I was getting worried at this point but the flames began to disipate. I had to put out a small fire inside the cockpit (Around the exhaust) were fuel had collected but that was all .. I'm just not sure we are ready for this kero start just yet as it draws about 20amp for around 30 seconds as I understand it. It's much simpliar to do some MAINTENANCE and change out fuel lines and a few Phesto fitting once in a while!! I have NEVER had any issues with my JAKADOFSKY Turbines EVER!!!

Dr.Tim

[Gary Travis]

Guys I figured it is time to get this up. For several months I have been testing a n electronic starting gas dump valve system for the turbines. It has worked well without problems. It consists of a electronic solenoid a valve and fittings. The dump valve system will come with all appropriate fittings and hoses.
It installs on all turbine engines and when connects to and open channel on the reciever. Once airbourne you hit the switch and the starting gas is dumped.
At present the kit is being packaged and the installation instructions are being written. It will be available in a few days to a week at most. You can PM me with questions, as soon as all is ready I will post ordering info.
Gary Travis

[wolfdad]

Dr. Tim,
Whole-heartedly concur and "good headwork" on letting it go.....you might have been far worse off had he shut down the turbine and airflow. Quite honestly, I am just not convinced that the kero-start option, and more specifically as an after-market "add-on" is a good idea. I think, once fully developed, and installed as an original manufacturer installation, warranted by the manufacturer, it "might" be an ok idea.

That having been said, I have never, with three Wrens and a Jakadofsky had any kind of start problems, other than the fuel pump problem I recently experienced and any "hot" or, more correctly identified "wet" starts were an "attention getter" for a split second, then were over with. I have no problem with the current procedure using Powermax or whatever start gas is recommended....what I DO have a problem with is carrying any kind of compressed, flammable gas onboard an aircraft....even the commericial carriers have a problem with that, although not for the same reasons, obviously. It is relatively easy to rig any turbine aircraft for an external start gas application and, once started, the gas is disconnected and the residual may be safely expelled from the container....on the ground.

Turbine starts for all intent and purpose are a controlled explosion reached by compressing air, mixing fuel into that compressed air, then igniting it. With our small guys, we use the Powermax start gas for a more instantaneous ignition fuel which brings the temps up rapidly enough to sustain combustion on kerosene only. The kero-start, as I understand it, provides a hotter ignition source via a hotter glow plus, plus adding more kerosene to the equation. Not properly installed or not properly working, you have a source for a protracted "wet"/"hot" start with free fuel continuing to burn (usually in the tailpipe area) with the turbine air flow fueling that fire (essentially how an afterburner on a tactical jet works). And, it's kinda' like having a tiger (500 lb ***** that will eat you) by the tail...you don't know whether to hang on or turn loose. In this situation, since we don't have any method for selectively securing the ignition discreetly, the best alternative is to allow the turbine to continue to start with the airflow eventually blowing the fire aft and out. To stop the start, allows the remaining fuel to burn internal to the turbine and aircraft and any fuel that per chance leaks out will be burning fuel, so I think you can see where I am going.

Enough of turbines 101. Kero-start may be the way to go in the future as original equipment, however my recommendation is not as an add-on.
Doc

[chopper jockey]

Dr Tim, of course over priming can happen whether you start on gas or kero, I`ve had flames shooting out the exhaust because my wren wouldn`t start on gas once, turns out It had a gas leak! and it was a cold day.

Gary, why not just activate the existing gas solenoid with an in-flight switch?

[cbergen]

That hot start was pretty intense, Dr. Tim. Glad you had the presence to shoot it just a tad with the extinguisher, or he could have lost the whole model!!

We all have to go on our own experiences here, but I think as long as the INSTRUCTIONS are followed, any of these systems can be as safe as another.

Some of the models currently on the market use plastic bottles for fuel tanks. Wouldn't you think in a crash that they might split, sending kerosene towards a hot engine and exhaust, possibly lighting it? I'm not bashing on another, just bringing up a point that these are models, they do crash on ocassion, but every scenario can't be ruled out unless we just don't fly the darn things!!

We did have another customer have a VERY large fireball when their propane line burst on landing. It took a little while to figure out why. They did not follow the instructions!! Our good friend Peter Wales had even posted some time ago about the dangers of using regular propane, which is exactly what they had done, instead of using the Powermax fuel as spelled out in the manual........

A kerosene fire may be harder to start than a propane one, but it would also be harder to put out, having more kerosene onboard with higher flow rates. The propane fire would burn out by itself pretty quick, A puddle of kerosene can burn for quite some time.

Just my thoughts and ramblings on the subject. :mrgreen:

[chopper jockey]

[quote]A kerosene fire may be harder to start than a propane one, but it would also be harder to put out, having more kerosene onboard with higher flow rates.
Chris, I don`t understand your statement, will you explain why you would have more kerosene on board and why would there be a higher flow rate :?

[cbergen]

[quote]A KEROSENE fire may be harder to start than a PROPANE one, but it would also be harder to put out, having more KEROSENE onboard with higher flow rates. The PROPANE fire would burn out by itself pretty quick, A puddle of KEROSENE can burn for quite some time.

Try reading the whole quote instead of picking and choosing my words.


There is a bit of a difference between the 44oz of kerosene on board vs the 2-4 oz of propane, is what I meant.


The higher flow rate refers to the kerosene being PUMPED to the engine, vs the couple of pounds of pressurized gas from the propane.

Don't try to read too much into what may be my erroneous descriptions of operation, these are just meant as generalizations.

[Dr.Tim]

So that everyone understands .. Chris was there when this HOT start happened with the Kero Start ... Intense is putting it mildly!! Luckly the gentelman continued the start. I could hear Chris in the background ..Oh MY, Oh My, Oh My!! :lol:


Dr.Tim

[Gary Travis]

Chopper Jockey
If you use the existing valve and release the gas into the already running engine you will see a temp rise. In my testing I found this to cause a flame out on several occasions. Going to the seperate valve and dump system it does not cause a rise in temp, there fore taking the temp problem out of th equasion.
Gary

[wolfdad]

Dr. Tim/Chris,
I knew both of you were present when this situation took place and, the three of us have "been around the block" enough times to know where we were all coming from and going. Once the kero goes from being a "wet (overprimed)" start to a "hot (ignited, pooled kero)" start, things happen very quickly. And, folks, yes, you can put a lit cigarette out in JP/kero (only heard that...never tried it), but once ignited, it is a ***** to get out...and try getting that ***** put out when the closest land is over 200 miles away...on the deck of a carrier....been there, done that and didn't want the t-shirt or ball cap.

Again, I am with Tim on this one in saying, we may not be ready for the trade-offs involved when it comes to kero-start. Nobody is bashing anyone, however, when and if a manufacturer comes out with the kero-start as standard equipment and is willing to warrant it as operational and will replace the engine and my heliopter if it "burns to the ground," maybe then I'll give 'er a try.

And, Gary, two totally different subjects here between the start gas and the kero-start. Jetcat, in anticipation of the AMA acting on the "no flammable compressed gas" onboard a turbine aircraft has such a setting on their ECU, so we don't need to go into Frankenstein's secret-squirrel lab and re-invent the wheel (as so many folks enjoy doing these days). If one manufacturer can do it, they all can and a simple change in ECU or FADEC programming can activate the start gas solenoid valve after a successful start and vent the remainder overboard through the turbine....geez, might increase TIT 6° on a hot day. Until that is available, I am starting with external gas. Absolutely no need for another valve, the $$$ involved or the additional weight and wiring.

Chris, thanks! Got the mounts today.
Doc

[cbergen]

I'm surprised you could here me, Dr. Tim, Over your own Girlish screams!! :lol:

You're more than welcome Doc, Hope they work for you.